Mail Archives: djgpp/1996/12/13/06:51:10
On Thu, 12 Dec 1996 19:06:38 -0800,
John M. Aldrich <fighteer AT cs DOT com> wrote:
>Jordy Potman wrote:
>>
>> Hello,
>>
>> I have just upgraded from DJGPP 2.00 to DJGPP 2.01. My program
>> ( a 3D graphics program) runs just fine build with DJGPP 2.00,
>> but if I rebuild it with the same makefile using DJGGP 2.01 it
>> runs about 30 times slower (The frame rate drops from 30 to 1 frame
>> per second). This happens only when the -pg option is turned on. Without
>> this option the program runs fine with DJGPP 2.01.
>>
>> I hope someone can explain me why there's such a big speed difference
>> between version 2.00 and 2.01.
>
>Profiling ALWAYS makes your program run slower - there's a tremendous
>amount of overhead involved in detecting each and every function call
>and storing the data. It doesn't matter whether it's on v2.00 or v2.01.
>
>Besides, in comparing profiling and non-profiling code, you are
>comparing apples and oranges. It would be more interesting if v2.00 and
>v2.01 differed when _both_ were compiled for profiling. If you do
>notice such a change, it's likely to be because the later version of the
>compiler has a more sophisticated, and thus slower, profiler.
>
>You're missing that critical question: how fast does it run under v2.00
>with -pg?
I think I have not missed the critical question, but I perhaps haven't
explained it clear enough. My problem is that my program runs at 30 frames
per second under v2.00 WITH -pg and it runs at about 1 fps under v2.01 with
-pg. Without -pg it runs at 30 frames per second under both v2.00 and v2.01.
I expected the change in speed had something to do with a better profiler
in the later version of the compiler, but this is quite a big difference.
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